Obstacle avoidance driver assistance systems are designed to modify vehicle behavior automatically if a vehicle encounters an obstacle in its path. If the obstacle is a preceding vehicle, and the vehicle encounters the preceding vehicle while accelerating or traveling with excessive speed, some driver assistance systems are designed to decelerate the vehicle automatically, for example, by counteracting driver inputs to an accelerator pedal with reactive force or by automatically applying the vehicle brakes. However, existing driver assistance systems are not designed to decelerate the vehicle through more direct interaction with the engine, for example, by sending commands to an engine controller related to throttle position or ignition timing.